以下是必需的程序。
public class Tester { public static int binarySearch(int arr[], int first, int last, int element){ int mid = (first + last)/2; while( first <= last ){ if ( arr[mid] < element ){ first = mid + 1; }else if ( arr[mid] == element ){ return mid; }else{ last = mid - 1; } mid = (first + last)/2; } return -1; } public static void main(String a[]) { int[] array = { 10, 20, 30, 40, 50, 60 }; int element = 50; int last=array.length-1; int index = binarySearch(array,0,last,element); if (index != -1) { System.out.println(element + " present at index: " + index); } else { System.out.println(element + " 不存在。"); } } }
输出结果
50 is present at index: 4